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Plant Physiology 134:352-360 (2004) © 2004 American Society of Plant Biologists Osmotic Effects on the Electrical Properties of Arabidopsis Root Hair Vacuoles in Situ1Biology Department, York University, Toronto, Ontario M3J 1P3, Canada
To assess the role of the vacuole in responses to hyperosmotic and hypo-osmotic stress, the electrical properties of the vacuole were measured in situ. A double-barrel micropipette was inserted into the vacuole for voltage clamping. A second double-barrel micropipette was inserted into the cytoplasm to provide a virtual ground that separated the electrical properties of the vacuole from those of the plasma membrane. Osmotic stress causes immediate electrical responses at the plasma membrane (Lew RR [1996] Plant Physiol 97: 2002-2005) and ion flux changes and turgor recovery (Shabala SN, Lew RR [2002] 129: 290-299) in Arabidopsis root cells. In situ, the vacuole also responds rapidly to changes in extracellular osmotic potential. Hyperosmotic treatment caused a very large increase in the ionic conductance of the vacuole. Hypo-osmotic treatment did not affect the vacuolar conductance. In either case, the vacuolar electrical potential was unchanged. Taken in concert with previous studies of changes at the plasma membrane, these results demonstrate a highly coordinated system in which the vacuole and plasma membrane are primed to respond immediately to hyperosmotic stress before changes in gene expression.
1 This work was supported by the Natural Sciences and Engineering Research Council of Canada (Discovery Grant). Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.103.031427. * Corresponding author; e-mail planters{at}yorku.ca; fax 416-736-5698. Received August 6, 2003; returned for revision September 4, 2003; accepted September 22, 2003. This article has been cited by other articles:
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